Valve cuff support

ABSTRACT

A prosthetic heart valve includes a stent having a collapsed condition and an expanded condition. The stent has a proximal end, a distal end and a plurality of cells, each cell being formed by a plurality of struts. A valve assembly is secured to the stent and includes a cuff and a plurality of leaflets. The plurality of leaflets are attached to the cuff adjacent an underwire that extends about the perimeter of the cuff.

CROSS REFERENCE TO RELATED APPLICATION

The application claims the benefit of the filing date of U.S. Provisional Patent Application No. 61/665,624 filed Jun. 28, 2012, the disclosure of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present invention relates to collapsible prosthetic heart valves having unique valve leaflet attachments.

Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.

Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two common types of stents on which the valve structures are ordinarily mounted: a self-expanding stent and a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve must first be collapsed or crimped to reduce its circumferential size and diameter.

When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and re-expanded to full operating use range. For balloon-expandable valves, this generally involves releasing the entire valve, assuring its proper location, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically expands as the sheath covering the valve is withdrawn.

Despite the various improvements that have been made to collapsible prosthetic heart valves, the currently available devices suffer from some shortcomings. For example, anatomical variations between patients may prevent adequate coaptation of the heart valve leaflets, and may further result in increased stresses at different portions of the heart valve, leading to valve failure. In addition, conventional delivery devices do not allow for sufficient operability of the valve leaflets during partial deployment.

There therefore is a need for further improvements in collapsible prosthetic heart valves and their method of manufacture. Among other advantages, the present invention may address one or more of these needs.

BRIEF SUMMARY OF THE INVENTION

In some embodiments, a prosthetic heart valve includes a stent having a collapsed condition and an expanded condition, the stent having a proximal end, a distal end and a plurality of cells, each cell being formed by a plurality of struts. The valve may further include an underwire disposed around the circumference of the stent and a valve assembly secured to the stent, the valve assembly including a cuff and a plurality of leaflets, the cuff being coupled to the underwire and the plurality of leaflets being attached to the cuff adjacent the underwire.

In some examples, the stent may include a plurality of commissure features and the underwire is coupled to the cuff with a repeating pattern, the pattern including a portion descending toward the proximal end of the stent, a portion ascending toward a commissure feature, and an intermediate portion between the descending portion and the ascending portion, the pattern being disposed solely between the commissure features and the proximal end of the stent. The underwire may be coupled to the plurality of commissure features. An end of the descending portion may be spaced between about 0.5 mm and about 2.0 mm proximally of a first commissure feature, and an end of the ascending portion is spaced between about 0.5 mm and about 2.0 mm proximally of a second commissure feature. The underwire may be coupled to the cuff with a plurality of stitches, the plurality of stitches also attaching the plurality of leaflets to the cuff. The underwire may form a repeating parabolic pattern.

In some examples, the cuff may be disposed inside of the stent, and at least a portion of the underwire passes between the cuff and the strut. At least a portion of the underwire may lie outwardly of the strut. The plurality of leaflets may be attached to the cuff and the underwire via at least one suture that pierces the cuff and at least one of the plurality of leaflets and wraps around the underwire before piercing the cuff a second time. The at least one suture may pierce the cuff and the at least one leaflet, and forms at least one complete loop around the underwire before piercing the cuff a second time. The plurality of leaflets may be attached to the cuff and the underwire via at least one suture that pierces the cuff, the underwire and at least one of the plurality of leaflets.

In some examples, the underwire includes a suture. In some examples, the underwire includes a braided suture. The underwire may also include a metal or a shape-memory wire that has been pre-set to form a shape corresponding to a contour of the cuff. At least a portion of the underwire may be radiopaque. At least a portion of the underwire may include tantalum.

In some embodiments, a prosthetic heart valve includes a stent having a collapsed condition and an expanded condition, the stent having a proximal end, a distal end and a plurality of cells, each cell being formed by a plurality of struts and a valve assembly secured to the stent, the valve assembly including a cuff and a plurality of leaflets, the cuff having a reinforcement region about the circumference of the cuff and the plurality of leaflets being attached to the cuff at the reinforcement region.

In some examples, the reinforcement region may form a repeating parabolic pattern about the circumference of the cuff. The reinforcement region may include a suture.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention are disclosed herein with reference to the drawings, wherein:

FIG. 1A is a partial side view of a conventional prosthetic heart valve showing a potential strain distribution profile in the valve assembly;

FIG. 1B is an enlarged partial view of the conventional prosthetic heart valve of FIG. 1A showing the strain distribution in the leaflet;

FIG. 2A is a highly schematic cross-sectional view of a portion of a collapsible prosthetic heart valve according to the present invention having folded leaflets sutured to the cuff;

FIG. 2B is an enlarged side view of a portion of a collapsible prosthetic heart valve according to the present invention showing a folded belly flap;

FIG. 3 is a partial developed view of a collapsible prosthetic heart valve according to the present invention showing the suturing pattern of the leaflets to the cuff;

FIG. 4 is an enlarged side view of a portion of the collapsible prosthetic heart valve of FIG. 3 showing the runner region between ancons;

FIGS. 5A and 5B depict side views of a collapsible prosthetic heart valve according to the present invention having a tissue pocket between the cuff and the leaflet, and a prior art device lacking such a pocket, respectively;

FIG. 6 is a partial side view of a prosthetic heart valve showing the leaflet-cuff attachment load distribution in the valve assembly;

FIG. 7A is a highly schematic perspective view of an underwire secured to a cuff;

FIG. 7B is a highly schematic top view of an underwire secured to a cuff;

FIG. 8 is a side view of a portion of a collapsible prosthetic heart valve having an underwire;

FIG. 9A is a side view of another collapsible prosthetic heart valve having an underwire;

FIG. 9B is an enlarged side view of a portion of the collapsible prosthetic heart valve of FIG. 9A showing the underwire crossing struts;

FIG. 10A is a highly schematic cross-sectional view of a portion of a collapsible prosthetic heart valve according to the present invention having a folded leaflet sutured to the underwire and the cuff;

FIG. 10B is a highly schematic cross-sectional view of a portion of another collapsible prosthetic heart valve according to the present invention having a folded leaflet sutured to the underwire and the cuff;

FIG. 10C is a highly schematic cross-sectional view of a portion of a further collapsible prosthetic heart valve according to the present invention having a folded leaflet sutured to the underwire and the cuff;

FIG. 11A is a side view of a leaflet folded over itself to produce a belly flap and secured via a reverse-running stitch;

FIG. 11B is a highly schematic cross-sectional view of a portion of a further collapsible prosthetic heart valve according to the present invention having a folded leaflet sutured to the underwire and the cuff through a reverse-running stitch; and

FIGS. 11C-P are highly schematic cross-sectional views of various configurations of attaching an underwire to a cuff; and

FIG. 12 is an x-ray showing a partial representative view of a radiopaque stent and underwire.

Various embodiments of the present invention will now be described with reference to the appended drawings. It is to be appreciated that these drawings depict only some embodiments of the invention and are therefore not to be considered limiting of its scope.

DETAILED DESCRIPTION

As used herein, the term “proximal,” when used in connection with a prosthetic heart valve, refers to the end of the heart valve closest to the heart when the heart valve is implanted in a patient, whereas the term “distal,” when used in connection with a prosthetic heart valve, refers to the end of the heart valve farthest from the heart when the heart valve is implanted in a patient. When used in connection with devices for delivering a prosthetic heart valve into a patient, the terms “proximal” and “distal” are to be taken as relative to the user of the delivery devices. “Proximal” is to be understood as relatively close to the user, and “distal” is to be understood as relatively farther away from the user.

FIG. 1A shows a typical collapsible prosthetic heart valve 100. The prosthetic heart valve 100 is designed to replace the function of a native aortic valve of a patient. Examples of collapsible prosthetic heart valves are described in International Patent Application Publication No. WO/2009/042196; U.S. Pat. No. 7,018,406; and U.S. Pat. No. 7,329,278, the disclosures of all of which are hereby incorporated herein by reference. As discussed in detail below, the prosthetic heart valve has an expanded condition and a collapsed condition. Although the invention is described herein as applied to a prosthetic heart valve for replacing a native aortic valve, the invention is not so limited, and may be applied to prosthetic valves for replacing other types of cardiac valves.

The prosthetic heart valve 100 includes a stent or frame 102, which may be wholly or partly formed of any biocompatible material, such as metals, synthetic polymers, or biopolymers capable of functioning as a stent. Suitable biopolymers include, but are not limited to, elastin, and mixtures or composites thereof. Suitable metals include, but are not limited to, cobalt, titanium, nickel, chromium, stainless steel, and alloys thereof, including nitinol. Suitable synthetic polymers for use as a stent include, but are not limited to, thermoplastics, such as polyolefins, polyesters, polyamides, polysulfones, acrylics, polyacrylonitriles, polyetheretherketone (PEEK), and polyaramides. The stent 102 may have an annulus section 110, an aortic section (not shown), and an intermediate section disposed between the annulus and aortic sections. Each of the annulus section 110, the intermediate section, and the aortic section of the stent 102 includes a plurality of cells 112 connected to one another around the stent. The annulus section 110, the intermediate section, and the aortic section of the stent 102 may include one or more annular rows of cells 112 connected to one another. For instance, the annulus section 110 may have two annular rows of cells 112. When the prosthetic heart valve 100 is in the expanded condition, each cell 112 may be substantially diamond shaped. Regardless of its shape, each cell 112 is formed by a plurality of struts 114. For example, a cell 112 may be formed by four struts 114.

The stent 102 may include commissure features or commissure posts (not shown) connecting at least two cells 112 in the longitudinal direction of the stent 102. The commissure features may include eyelets that facilitate the suturing of a valve assembly 104 to the sent 102.

The prosthetic heart valve 100 also includes a valve assembly 104 attached inside the annulus section 110 of the stent 102. United States Patent Application Publication No. 2008/0228264, filed Mar. 12, 2007, and United States Patent Application Publication No. 2008/0147179, filed Dec. 19, 2007, the entire disclosures of both of which are hereby incorporated herein by reference, describe suitable valve assemblies. The valve assembly 104 may be wholly or partly formed of any suitable biological material, fabric or a polymer. Examples of biological materials suitable for the valve assembly 104 include, but are not limited to, porcine or bovine pericardial tissue. Examples of polymers suitable for the valve assembly 104 include, but are not limited to, polyurethane and polyester.

The valve assembly 104 may include a cuff 106 disposed on the lumenal surface of annulus section 110, on the ablumenal surface of the annulus section, or on both surfaces, and the cuff may cover all or part of either or both of the lumenal and ablumenal surfaces of the annulus section. FIG. 1A shows cuff 106 disposed on the lumenal surface of annulus section 110 so as to cover part of the annulus section while leaving another part thereof uncovered. In addition to the materials for forming valve assembly 104 noted above, the cuff 106 and/or any of the sutures described herein may include ultra-high-molecular-weight polyethylene. The valve assembly 104 may further include a plurality of leaflets 108 which collectively function as a one-way valve.

The cuff 106 of the prosthetic heart valve 100 of FIG. 1A tends to experience relatively high strain and/or stress at certain locations. In such heart valves 100, the pressure of blood that leaflets 108 keep from flowing into the heart may subject leaflets 108 to a load in the direction indicated by arrow L, shown in FIG. 1B. This load may cause high stress and/or strain on the cuff and/or leaflets. Moreover, a typical load may cause wear over time. To manage the increased stress and strain on the cuff 106, some conventional heart valves 100 have made the cuff thicker. However, thicker cuffs generally lead to a larger heart valve that is more difficult to deliver and implant.

Another method of redistributing the load has been to attach the leaflets to the struts. This too has been problematic. For a host of reasons outlined below, in accordance with some embodiments of the present invention, it may be advantageous to attach the leaflets substantially entirely to the cuff and not to the struts.

First, in certain procedures, collapsible valves may be implanted in a native valve annulus without first resecting the native valve leaflets. The collapsible valves may have critical clinical issues because of the nature of the stenotic leaflets that are left in place. Additionally, patients with uneven calcification, bi-cuspid disease, and/or valve insufficiency may not be able to be treated well, if at all, with the current collapsible designs.

Implantation of a prosthetic valve adjacent unevenly calcified leaflets could lead to several problems such as: (1) perivalvular leakage (PV leak), (2) valve migration, (3) mitral valve impingement, (4) conduction system disruption, (5) coronary blockage, etc., all of which can have severely adverse clinical outcomes. To reduce these adverse events, the optimal valve would seal and anchor adequately without the need for excessive radial force, protrusion into the left ventricular outflow tract (LVOT), etc., that could harm nearby anatomy and physiology. Embodiments of the present invention which attach the leaflets mainly to the cuff are able to achieve better coaptation of the leaflets, reducing the risk of leakage.

Second, the annulus section of the prosthetic valve may have a generally regular cylindrical shape by which is meant that the structure has a generally circular cross-section with a substantially constant diameter along its length. When placed in the annulus of a native heart valve, such as, for example, the tricuspid aortic valve, and expanded, a substantially fluid-tight fit should result. However, the native valve annulus may not be circular, and, in fact, may vary from patient to patient, as may the shape of the aortic sinus or aorta, the angle of the junction between the valve annulus and the aortic sinus, and other local anatomical features. When a prosthetic valve is deployed and expanded, it must accommodate these anatomical variations in order to function properly. This may result in distortion of the shape of the stent and/or valve assembly, and the repositioning of leaflets relative to one another, which can affect the coaptation of these leaflets.

As the stent of a collapsible prosthetic heart valve distorts during implantation, during beating of the heart, or because of irregularities in the patient's anatomy or the condition of the native valve, such distortion may be translated to the valve assembly, such that not all of the valve leaflets meet to form effective coaptation junctions. This can result in leakage or regurgitation and other inefficiencies which can reduce cardiac performance. Moreover, if the prosthetic valve is not placed optimally and the valve leaflets are not coapting as intended, other long term effects, such as uneven wear of the individual leaflets or increased stress on cuff and/or stent, can be postulated.

Prosthetic valves in accordance with certain aspects of the present invention, however, can function properly notwithstanding the distortion of the stent and/or valve assembly because the leaflets are substantially attached to the cuff and not to the stent. Without wishing to be held to any particular theory, it is believed that a valve design having leaflets mostly sewn to the cuff may be better able to adjust to less than perfect annulus geometry. Such leaflet-cuff arrangements may be more insulated from imperfect geometry-induced stresses on the struts than those arrangements having the leaflets completely or predominantly sewn to the stent. Thus, the possibility of uneven wear due to anatomical variations is greatly reduced by attaching the leaflets entirely or predominantly to the cuff.

Moreover, by sewing the leaflet to the cuff and not to the struts, greater flexibility is afforded in positioning the leaflets and in varying the height, width and shape of the leaflets. Specifically, because the leaflets in conventional heart valves are attached to the struts, the leaflet shape and positioning is limited by the location of the struts. In contrast, suturing patterns may be varied with greater benefits when the leaflets are attached predominantly to the cuff.

Having outlined some of the benefits of a leaflet-cuff attachment, the features of this embodiment will be described in connection with the prosthetic heart valve 300 shown in FIGS. 2A-5. It will also be noted that while the inventions herein described are predominately discussed in terms of a tricuspid valve and a stent having a shape as illustrated in FIGS. 2A-5, the valve could be a bicuspid valve, such as the mitral valve, or include more than three leaflets and the stent could have different shapes, such as a flared or conical annulus section, a less-bulbous aortic section, and the like, and a differently shaped intermediate section.

In attaching the plurality of leaflets, each leaflet 308 may be first attached to the stent 302 by suturing through the eyelets of commissure features 316. Additional examples of leaflet-commissure feature attachments are disclosed in U.S. patent application Ser. No. 13/216,124, entitled “Leaflet Suturing to Commissure points for Prosthetic Heart Valve”, filed on Aug. 23, 2011, the disclosure of which is hereby incorporated by reference as if fully set forth herein. In addition to the commissure features 316, the plurality of leaflets may be attached to the cuff 306 as described below.

FIGS. 2A, 2B and 3 illustrate one such embodiment in which the leaflets 308 have been attached by suturing substantially entirely to the cuff 306. In the illustrated embodiment, the leaflets 308 are coupled to the cuff 306 after they have been attached to the commissure features 316. It will be understood, however, that the order of attachment may be changed or varied as necessary by those skilled in the art.

FIGS. 2A and 2B illustrate a cuff 306 and one or more leaflets 308. Each leaflet 308 includes a proximal end 352 for attachment to the cuff 306 and a free distal end 354 for coapting with the other leaflets to form a closed valve. As seen in FIG. 2A, each leaflet 308 may be folded upon itself at the proximal end 352 to form a belly flap 356 for attaching the leaflet to the cuff 306. The belly flap 356 may be formed by folding the proximal edge of the leaflet 308 once over itself toward the cuff 306 so that the belly flap is disposed between a portion of the leaflet and the cuff. The width x of the belly flap 356 between folded edge 356 a and free edge 356 b may vary from valve to valve, and also within a valve. For example, the belly flap 356 may have a width x between about 0.1 mm and about 2.0 mm. Variants of the belly flap 356 are also contemplated herein. For example, the belly flap 356 may be formed by folding the leaflet 308 more than once (e.g., twice, thrice or more). Additionally, the belly flap 356 may be formed along only a portion of the proximal edge of the leaflet 308 if the entire proximal edge will not be sutured to the cuff 306. Still further, the belly flap 356 may be formed by folding the proximal edge of the leaflet 308 away from the cuff 306, rather than toward the cuff as described above.

After folding each leaflet 308 to form a belly flap 356, the leaflets 308 may be attached to the cuff 306 in accordance with the attachment pattern shown in FIG. 3. For the purpose of clarity, the leaflet-cuff attachment pattern will be described with reference to FIG. 3 without showing a belly flap. It will be understood, however, that a belly flap as described above and shown in FIGS. 2A and 2B may be disposed either on the inner or lumenal side of the leaflet 308 or between the leaflet and the cuff 306.

The prosthetic heart valve 300 of FIG. 3 includes a stent or frame 302 having an annulus section 310 and an aortic section (not shown). Each of the annulus section 310 and the aortic section of the stent 302 includes a plurality of cells 312 connected to one another around the circumference of the stent. The annulus section 310 and the aortic section of the stent 302 may include one or more annular rows of cells 312 connected to one another. For instance, the annulus section 310 may have two annular rows of cells 312. When the prosthetic heart valve 300 is in the expanded condition, each cell 312 may be substantially diamond shaped. Regardless of its shape, each cell 312 is formed by a plurality of struts 314. For example, a cell 312 may be formed by four struts 314.

The stent 302 may include commissure features 316 connecting at least two cells 312 in the longitudinal direction of the stent. The commissure features 316 may include eyelets for facilitating the suturing of a valve assembly 304 to the stent 302.

A cuff 306 may be disposed on the lumenal surface of annulus section 310, on the ablumenal surface of the annulus section, or on both surfaces, and the cuff may cover all or part of either or both of the lumenal and ablumenal surfaces of the annulus section. FIG. 3 shows cuff 306 disposed on the lumenal surface of annulus section 310 so as to cover part of the annulus section while leaving another part thereof uncovered. In particular, the cuff 306 covers substantially all of the annulus section 310 between the proximal edge of stent 302 and the commissure features 316, but a much lesser area of the annulus section between the commissure features. The valve assembly 304 may further include a plurality of leaflets 308 which collectively function as a one-way valve.

As shown in FIG. 3, struts 314 a, 314 b, and 314 c may be connected to one another in substantially end-to-end fashion diagonally along three cells 312, beginning with an end of the strut 314 a connected to a commissure feature 316 a and ending with an end of strut 314 c connected to an end of strut 314 d. Struts 314 c and 314 d are part of the same cell 312 a. Struts 314 d, 314 e, and 314 f may be connected to one another in substantially end-to-end fashion diagonally along three cells 312, beginning with an end of the strut 314 f connected to a commissure feature 316 b and ending with the connection between an end of strut 314 d and an end of strut 314 c. For the sake of completeness, cell 312 a includes strut 314 c connected to strut 314 d at the bottom of the cell and struts 314 g and 314 h connected to one another at the top of the cell, as well as to struts 314 d and 314 c, respectively.

In addition to being connected to one another around the circumference of stent 302, cells 312 may be connected to one another in the longitudinal direction of the stent. Two adjacent struts, for example struts 314 e and 314 g, merge near the bottom of the cell before splitting off into two different struts. The meeting point where two struts 314 merge or where one strut splits into two components is defined as an ancon 320. The ancons 320 in two longitudinally adjacent rows of cells 312 may be joined by runners r.

The plurality of leaflets 308 may be attached directly to the cuff 306 near struts 314 a, 314 b, 314 e, and 314 f, such as by suturing. As shown in FIG. 3, the leaflets 308 may be attached to cuff 306 just proximally of the aforementioned struts 314 along an attachment line R. Specifically, a distance y may be maintained between the attachment line R and the struts 314. This distance may be greater than, less than or equal to 2.0 mm, and may vary as necessary. By attaching the leaflets 308 to the cuff 306 in a pattern that follows the curvature of some of the struts 314, stress on the cuff 306 may be reduced while maintaining a degree of flexibility.

As described above, the attachment line R includes an initial descent from just proximal of commissure feature 316 a and continues proximally of struts 314 a and 314 b while substantially maintaining a distance y from the struts. At the proximal end of strut 314 b, the attachment line R begins to flatten out, passing through cell 312 a, and then ascends proximally of struts 314 e, 314 f, maintaining substantially the same or a similar distance y from the struts, until it reaches a point just proximal of commissure feature 316 b. Between the descending seam and the ascending seam, the attachment line may cross a pair of runners r1 and r2 and forms a vertex therebetween. In at least some other examples, attachment line R may pass above or below at least one of the runners r1 and r2.

FIG. 4 shows runners r1 and r2 in more detail. As described above, the attachment line R generally descends from a point just proximal of commissure feature 316, travels proximally of struts 314 a and 314 b, crosses runner r1, changes direction and crosses runner r2, and then ascends proximally of struts 314 e and 314 f until it reaches a point just proximal of commissure feature 316 b.

The foregoing discussion describes the general pattern by which leaflets 308 may be attached directly to cuff 306. Having generally described the attachment pattern, the following description provides one exemplary method of suturing the leaflets 308 to the cuff 306. As will be understood by those of ordinary skill in the art, the description below is for one of many possible methods, and the distances, configurations and arrangements described are merely exemplary and not limiting. For example, instead of using a single suture around the perimeter of the valve assembly, leaflets 308 may be sutured to the cuff 306 using a plurality of sutures, a staple, bioglue or any other suitable method of attachment.

Initially, the leaflets 308 are aligned with the cuff 306 and struts 314 at the desired locations, typically in the annulus section 310. The ends of the distal free edge of each leaflet 308 are then sutured to both the cuff 306 and the stent 302 through the eyelets of an adjacent pair of commissure features 316. The belly of the leaflets 308 may then be sutured to the cuff 306 around the circumference of the heart valve 300 proximally of the commissure features 316.

With reference to FIG. 3, a first leaflet 308 may be sutured to the cuff 306 by first passing a suture from the ablumenal side of the cuff 306 to the lumenal side of the cuff about 0.5 mm to about 2.0 mm proximally of a first commissure feature 316 a. This location will be referred to as the origination stitch. A suture tail segment may be maintained at the origination stitch in order to tie to the end of the pattern after stitching around the circumference of the cuff 306 has been completed. The leaflet 308 may then be stitched to the cuff 306 using a series of whip stitches. In at least some other examples, a running, or reverse-running stitch may be used instead of a whip stitch. Stitches from the ablumenal side to the lumenal side of the heart valve 300 pass through the cuff 306 only. Stitches from the lumenal side to the ablumenal side of the heart valve 300 pass through both layers of the leaflet 308 (e.g., the leaflet as well as the folded belly flap 356) and the cuff 306. Thus, with each whip stitch the suture is passed from the ablumenal side to the lumenal side of the heart valve 300 through the cuff 306 only and then through both layers of the leaflet 308 and the cuff 306 from the lumenal side of the valve to the ablumenal side thereof.

The stitch spacing and bite size may vary. In at least some examples, the stitch spacing and bite size may be from about 0.5 mm to about 2.0 mm, and preferably is about 1.0 mm. Stitches may be approximately perpendicular to the leaflet edge when viewed from the side of the valve 300. Beginning just proximally of commissure feature 316 a, the sutures may travel approximately at a distance y proximally of struts 314 a and 314 b, across a first runner r1, form a vertex, across a second runner r2, and approximately at a distance y proximally of struts 314 e and 314 f until reaching a point just proximal of commissure feature 316 b. The sutures may begin at a point A about 0.5 mm to about 2.0 mm proximal of commissure feature 316 a, and may end at a point B, about 0.5 mm to about 2.0 mm proximal of commissure feature 316 b.

Thus, between the first commissure feature 316 a and the second commissure feature 316 b, a substantially symmetrical parabola is formed by the suture line R. This parabolic pattern may be repeated between commissure features 316 b and 316 c and between commissure features 316 c and 316 a around the circumference of the cuff 306, ending at or near point A where the suture line R began. Upon returning to point A, the concluding tail of the suture line R may be tied to the origination stitch using a single double knot or any other suitable knot.

FIG. 5 shows a comparison between a heart valve 300 according to one embodiment of the present invention and a conventional heart valve 300′. As can be seen, the heart valve 300 according to the present invention includes an enlarged cuff 306 that overlaps with a portion of the leaflets 308. In contrast, the heart valve 300′ includes no such overlap between the leaflets 308′ and the cuff 306′. Rather, the leaflets 308′ and cuff 306′ are attached to one another in an edge-to-edge fashion. The leaflet-cuff overlap provided by the heart valve 300 of the present invention forms a pocket P and allows for the suture pattern discussed above. Pocket P formed by the leaflet-cuff overlap minimizes perivalvular leakage and acts as a tissue buffer for improved durability. Compared to conventional devices, this configuration also provides a larger buffer against fretting corrosion. Thus, by providing an enlarged cuff, the stress on the cuff may be decreased, the durability of the cuff increased and the flexibility of the heart valve increased to allow for applications such as partial deployment of the heart valve, for example, for testing.

In this manner, by attaching the leaflets 308 to the cuff 306, a host of benefits as enumerated above, as well as others, may be achieved. Moreover, the description above provides one method by which stress on the cuff can be reduced. Namely, by suturing the leaflets to the cuff, maintaining the spacing between the suture line and the struts described above, and passing the sutures across the runners, the load on the cuff can be partially redistributed to the struts to prevent possible wear and/or failure. Thus, the foregoing embodiment describes one method for reducing stress on the cuff at critical junctions. This method provides a solution by suturing the leaflets to the cuff without providing a thicker cuff or using different materials for the cuff.

The above embodiment notwithstanding, it will be understood that the leaflets need not be coupled only (except for the commissure features) to the cuff. In other embodiments, instead of suturing the leaflets to only the cuff, selected regions of each leaflet, or the proximal edge thereof, may be attached to an underwire disposed on or coupled to the cuff to relieve additional stress from the cuff. These embodiments will be described in more detail with reference to FIGS. 6A-11.

FIG. 6 is a partial side view of a prosthetic heart valve 600 having a stent 602 and a valve assembly 604 disposed in the annulus section 610 of the stent. Within the heart valve 600, leaflets 608 are attached to cuff 606 via sutures. Specifically, FIG. 6 shows a potential leaflet-cuff attachment load distribution in the valve assembly. When leaflets 608 coapt to form a closed configuration, load is transferred from the leaflet structure to the attachment points along the leaflet edge. As described in the above embodiments, these attachment points coincide with attachment line R. The load distribution diagram shows that high point loads are generated at individual sutures at certain regions L along attachment line R. If the point loads at regions L are sufficiently high, they will rip the suture through the cuff 606. Thus, regions L may be prone to failure. This failure may occur by ripping of the cuff 606, the leaflet 608, the sutures attaching the cuff 606 to the leaflet 608 or any combination thereof.

According to the present invention, a suture underwire may be attached to the prosthetic heart valve externally of the cuff to redistribute the load at the points at which the leaflets attach to the cuff, reducing the risk of valve structural damage due to a break in the joint/subassembly formed between the cuff and the leaflet attachment line R. Without being bound to any particular theory, it is believed that the underwire may improve cuff durability, improve valve function, reduce perivalvular leakage due to cuff billowing, achieve an optimal leaflet contour and aid in reducing the implant catheter profile.

FIG. 7A is a highly schematic view of an underwire 730 secured to a cuff 706 according to an embodiment of the present invention. The underwire 730 may be formed of a suture, wire, fabric, polymers, reinforced polymers, a metal such as nitinol, a biomaterial such as pericardial tissue, stainless steel or the like, or any combination thereof, such as a braided wire or metal-suture combination. In some examples, underwire 730 is formed of a ultra high molecular weight polyethylene, such as FORCE FIBER®. The underwire 730 may also be formed as a solid rod, a tube or a wire to provide support at certain portions of the cuff 706. In one specific embodiment, the underwire 730 may be formed of a nitinol wire that is heat-set to the counter of the cuff 706. As seen in the schematic view of FIG. 7A, the underwire 730 may be attached to the cuff in a parabolic pattern complementing attachment line R. The attachment patterns and configurations of underwire 730 will be discussed in more detail below. It is sufficient from this diagram and from the highly schematic diagram of FIG. 7B to appreciate that the underwire 730 will assist in supporting the suturing between the cuff 706 and the leaflets 708 by providing a reinforcement to redistribute the load between the leaflets and the cuff.

FIGS. 8, 9A and 9B describe several patterns for attaching the underwire to the cuff. Though these specific attachment patterns are described herein, it will be understood that any of the patterns described above with reference to attachment line R of FIG. 3 may be used for attaching the underwire to the cuff. The attachment line may be sutured directly onto or through the underwire to provide additional support. Moreover, it will be understood that the underwire may be attached to the cuff prior to suturing the leaflets to the cuff. For example, the underwire may be attached to the cuff before attaching the cuff to the stent or after attaching the cuff to the stent. Additionally, the underwire may be attached to the cuff at the same time that the leaflets are sutured to the cuff.

In a first example, shown in FIG. 8, a prosthetic heart valve 800 includes a stent 802 and a valve assembly 804 disposed in the annulus section 810 of the stent. A cuff 806 is attached to the stent 802 on the luminal side of annulus section 810. As shown in FIG. 8, stent 802 includes a plurality of stents 814 connected to one another to define open cells 812. Struts 814 a, 814 b, and 814 c may be connected to one another in substantially end-to-end fashion diagonally along three cells 812, beginning with an end of the strut 814 a connected to a commissure feature 816 a and ending with an end of strut 814 c connected to an end of strut 814 d. Struts 814 c and 814 d are part of the same cell 812 a. For the sake of completeness, cell 812 a includes strut 814 c connected to strut 814 d at the bottom of the cell and struts 814 g and 814 h connected to one another at the top of the cell, as well as to struts 814 d and 814 c, respectively.

Underwire 830 may form a pattern around the circumference of cuff 806. As with the attachment line R described above, the pattern of underwire 830 may likewise include an initial descent from just proximal of commissure feature 816 a and continues proximally of struts 814 a and 814 b while substantially maintaining a distance y from the struts. At the proximal end of strut 814 b, the pattern of underwire 830 begins to flatten out, passing through cell 812 a, and then ascends proximally of the next set of struts (not shown in FIG. 8), until it reaches a point just proximal of the next commissure feature. It should be noted that the underwire 830 in FIG. 8 is attached to the cuff 806 and is disposed between the cuff and the stent 802. With this arrangement, loads from the underwire 830 are distributed directly to the cuff 806 only and not to the struts 814. Additionally, the pattern of underwire 830 in the embodiment of FIG. 8 begins and ends at points proximal of the commissure features 816 as discussed.

FIG. 9A is a side view of a second example of the attachment of an underwire 930 to a cuff 906. The prosthetic heart valve 900 is similar to the prosthetic heart valve 800 described above, and therefore like elements are identified by like reference numerals that begin with the numeral “9”, instead of the numeral “8”. The manner of attachment for underwire 930 is similar to the manner of attachment for underwire 830, with two exceptions. First, underwire 930 is attached directly to commissure features 916 instead of ending at points proximal of the commissure features. In addition, the underwire 930 is disposed outwardly of stent 902 as shown in the enlarged view of FIG. 9B. That is, stent 902 is disposed between cuff 906 and underwire 930. By attaching underwire 930 to the commissure features 916 and/or by passing underwire 930 outwardly of stent 902, loads may be redistributed from the underwire to the stents 914.

It will be understood that any combination of these arrangements may be utilized to attach the underwire 930 to the cuff 906. For example, underwire 930 may be arranged between cuff 906 and stent 902 as described in FIG. 8, but also may attach to the commissure features 916 as described in FIG. 9. Alternatively, underwire 930 may be arranged outwardly of stent 902 at select points only or be attached to select commissure features. In this manner, the load may be distributed from the underwire to the cuff and/or the stent as desired.

Having described the manner of attaching the underwire to the cuff and stent, some possible arrangements for attaching the leaflets to the cuff and underwire will now be described. Several alternatives for such attachment are shown in FIGS. 10A-C.

FIG. 10A is a highly schematic cross-sectional view of a portion of a collapsible prosthetic heart valve 1000 according to one example of the present invention. Heart valve 1000 has leaflets 1008 sutured to both an underwire 1030 and a cuff 1006. Each leaflet 1008 may be folded upon itself at its proximal end to form a belly flap 1056 for attaching the leaflet 1008 to the cuff 1006. The belly flap 1056 may take any of the configurations or arrangements discussed above with reference to FIG. 2A or may not include a fold at all. The structure of heart valve 1000 as described in connection with FIG. 10A may be the same for FIGS. 10B and 10C.

The manner in which leaflets 1008 are attached to cuff 1006 and underwire 1030, as in FIG. 10A, will be referred to as the “wrapped” configuration. In this wrapped configuration, leaflet 1008 is folded upon itself to form belly flap 1056. A suture T begins from the interior of valve 1000 and passes through the leaflet 1008, the leaflet belly flap 1056, and the cuff 1006. The suture T then wraps around underwire 1030 and is passed back toward the interior of the valve through the cuff 1006 and under the folded edge of leaflet 1008, creating a whip stitch. This stitch pattern may be repeated around the entire circumference of valve 1000 to secure each of leaflets 1008 and underwire 1030 to cuff 1006.

A second configuration, shown in FIG. 10B, will be referred to as the “pierced” configuration. In the pierced configuration, the suture T begins at the interior of valve 1000 and is passed through the leaflet 1008, the belly flap 1056 and the cuff 1006. Instead of wrapping around underwire 1030, the suture is pierced through underwire 1030 and passed back toward the interior of the valve through the cuff 1006 and under the folded edge of leaflet 1008. This stitch pattern may be repeated around the entire circumference of valve 1000 to secure each of leaflets 1008 and underwire 1030 to cuff 1006.

In a third configuration, the underwire 1030 is cinched as shown in FIG. 10C. The “cinched” configuration may begin in a manner similar to the wrapped configuration of FIG. 10A, with suture T passing from the interior of the valve 1000 through leaflet 1008, belly flap 1056 and cuff 1006. Suture T may then be wrapped in a full loop around the underwire 1030 and then passed back to the interior of the valve through cuff 1006 and under the folded edge of leaflet 1008. It will be understood that this cinched configuration is not limited to a single loop around underwire 1030, and that suture T may wrap around the underwire 1030 any number of revolutions as desired before passing back to the interior of the valve.

In another configuration, shown in FIGS. 11A and 11B, leaflet 1008 is folded over itself to form belly flap 1056 and a reverse-running stitch B holds belly flap 1056 to leaflet 1008 to create a thickened portion, which will then be coupled to cuff 1006. Heart valve 1000 has leaflets 1008 sutured to both an underwire 1030 and a cuff 1006 as shown in FIG. 11B. Specifically, a suture T passes through reverse-running stitch B the leaflet 1008, the leaflet belly flap 1056, the other side or revere-running stitch B and the cuff 1006. The suture T then wraps around underwire 1030 and is passed back toward the interior of the valve through the cuff 1006 and under the folded edge of leaflet 1008, creating a whip stitch. This stitch pattern may be repeated around the entire circumference of valve 1000 to secure each of leaflets 1008 and underwire 1030 to cuff 1006. Folding leaflet 1008 over itself to create a belly flap and using a reverse-running stitch B to secure the two together produces a thickened portion that provides enhanced structure integrity for attaching to cuff 1006 and underwire 1030.

FIGS. 11C-P are highly schematic cross-sectional views of various configurations of attaching underwire 1030 to a cuff 1006. As will be appreciated from these figures, suture T may pass through or around any combination of the reverse-running stitch B, leaflet 1008, belly flap 1056 and cuff 1006. In addition to these configurations, underwire 1030 may be moved to a different location, or multiple underwires may be utilized. For example, a second underwire 1030 may be disposed between leaflet 1008 and belly flap 1056 to form the thickened portion in addition to underwire 1030 disposed outside cuff 1006. Underwire could also be disposed inside cuff 1006 (e.g., between cuff 1006 and belly flap 1056) or any other suitable position so long as it helps redistribute load over the cuff and helps prevent tearing of the cuff.

In other variations, underwire 1030 may be disposed over the stent struts in certain portions and under the stent struts in other portions. Underwire 1030 may also be weaved in and out of cuff 1006, and may be attached to the commissure features to provide additional support. Additionally, underwire 1030 need not be continuous and may be formed of discontinuous portions disposed around the circumference of the heart valve.

Moreover, though the previous configurations have shown a leaflet 1008 folded over toward the cuff 1006 to form a belly flap 1056, it will be appreciated that cuff-leaflet assembly, also referred to as a belly attachment contour, is not limited to this configuration. In other examples, the cuff-leaflet assembly includes a leaflet that is folded away from cuff 1006 to form a belly flap 1056 on a side of the leaflet 1008 opposite the cuff. Additionally, leaflet 1008 of the leaflet-cuff assembly need not form a belly flap 1056 at all but may lay flat against cuff 1006. It is contemplated that cuff 1006 itself may be folded over and that multiple reverse-running stitches may be utilized instead of a single stitch as described above.

In addition to providing support and redistributing the load at the cuff-leaflet attachment, the underwire may provide other benefits. For example, FIG. 12 is an x-ray showing a partial perspective view of a stent 1202 with a radiopaque underwire 1230. Underwire 1230 may be constructed of a barium or tantalum-doped braid allowing for the leaflet belly flap to be easily identified under fluoroscopy. Though tantalum has been used as an example, it will be understood that any other suitable material capable of visualization under fluoroscopy may be used to construct or dope a portion of underwire 1230. This embodiment may also be useful in lining up the valve with another device or valve.

In operation, any of the embodiments of the prosthetic heart valve described above may be used to replace a native heart valve, such as the aortic valve. The prosthetic heart valve may be delivered to the desired site (e.g., near a native aortic annulus) using any suitable delivery device. During delivery, the prosthetic heart valve is disposed inside the delivery device in the collapsed condition. The delivery device may be introduced into a patient using a transfemoral, transapical, transseptal or other approach. Once the delivery device has reached the target site, the user may deploy the prosthetic heart valve. Upon deployment, the prosthetic heart valve expands into secure engagement within the native aortic annulus. When the prosthetic heart valve has been properly positioned inside the heart, it works as a one-way valve, allowing blood to flow in one direction and preventing blood from flowing in the opposite direction.

Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. For example, in some embodiments, the underwire may include certain anchoring features, such as barbs for anchoring the heart valve. In at least some other embodiments, the underwire may include a surface finish or be doped with drugs or other material to ensure tissue ingrowth and sealing. Moreover, while the preceding discussion has provided examples by way of folded leaflets, it will be understood that the leaflet need not be folded and that the heart valve may instead include a belly attachment contour having a flat leaflet instead of a folded leaflet. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.

It will be appreciated that the various dependent claims and the features set forth therein can be combined in different ways than presented in the initial claims. It will also be appreciated that the features described in connection with individual embodiments may be shared with others of the described embodiments. 

The invention claimed is:
 1. A prosthetic heart valve, comprising: a stent having a collapsed condition and an expanded condition, the stent having a proximal end, a distal end and a plurality of cells, each cell being formed by a plurality of struts; an underwire disposed around a perimeter of the stent; and a valve assembly secured to the stent, the valve assembly including a cuff and a plurality of leaflets, each of the plurality of leaflets having a pair of attachment portions, a free edge extending between the pair of attachment portions, and a belly portion extending between the pair of attachment portions and disposed opposite the free edge, a portion of the underwire having a shape that conforms to belly portions of the plurality of leaflets, the cuff being coupled to the underwire and the plurality of leaflets, and the cuff being disposed between the underwire and portions of the plurality of leaflets; wherein the stent includes a plurality of commissure features and the underwire is coupled to the cuff with a repeating pattern, the pattern including a descending portion extending toward the proximal end of the stent, an ascending portion extending toward a commissure feature, and an intermediate portion between the descending portion and the ascending portion, the pattern being disposed solely between the commissure features and the proximal end of the stent.
 2. The prosthetic heart valve according to claim 1 , wherein the underwire is coupled to the plurality of commissure features.
 3. The prosthetic heart valve according to claim 1, wherein an end of the descending portion is spaced between 0.5 mm and 2.0 mm proximally of a first commissure feature, and an end of the ascending portion is spaced between 0.5 mm and 2.0 mm proximally of a second commissure feature.
 4. The prosthetic heart valve according to claim 1, wherein the underwire forms a repeating parabolic pattern.
 5. The prosthetic heart valve according to claim 4, wherein at least a portion of the underwire lies on an abluminal surface of the stent.
 6. The prosthetic heart valve according to claim 1, wherein the underwire comprises a suture.
 7. The prosthetic heart valve according to claim 6, wherein the underwire comprises a braided suture of multiple materials.
 8. The prosthetic heart valve according to claim 1, wherein the underwire comprises a metal.
 9. The prosthetic heart valve according to claim 1, wherein the underwire comprises a shape-memory wire that has been pre-set to form a shape corresponding to a contour of the cuff.
 10. The prosthetic heart valve according to claim 1, wherein at least a portion of the underwire is radiopaque.
 11. The prosthetic heart valve according to claim 10, wherein at least a portion of the underwire includes tantalum.
 12. The prosthetic heart valve according to claim 1, wherein a portion of the underwire is coupled to the belly portion of each of the plurality of leaflets.
 13. A prosthetic heart valve comprising: a stent having a collapsed condition and an expanded condition, the stent having a proximal end, a distal end and a plurality of cells, each cell being formed by a plurality of struts; an underwire disposed around a perimeter of the stent; and a valve assembly secured to the stent, the valve assembly including a cuff and a plurality of leaflets, each of the plurality of leaflets having a pair of attachment portions, a free edge extending between the pair of attachment portions, and a belly portion extending between the pair of attachment portions and disposed opposite the free edge, a portion of the underwire having a shape that conforms to belly portions of the plurality of leaflets, the cuff being coupled to the underwire and the plurality of leaflets, and the cuff being disposed between the underwire and portions of the plurality of leaflets; wherein the underwire is coupled to the cuff with a plurality of stitches, the plurality of stitches also attaching the plurality of leaflets to the cuff.
 14. A prosthetic heart valve comprising: a stent having a collapsed condition and an expanded condition, the stent having a proximal end, a distal end and a plurality of cells, each cell being formed by a plurality of struts; an underwire disposed around a perimeter of the stent; and a valve assembly secured to the stent, the valve assembly including a cuff and a plurality of leaflets, each of the plurality of leaflets having a pair of attachment portions, a free edge extending between the pair of attachment portions, and a belly portion extending between the pair of attachment portions and disposed opposite the free edge, a portion of the underwire having a shape that conforms to belly portions of the plurality of leaflets, the cuff being coupled to the underwire and the plurality of leaflets, and the cuff being disposed between the underwire and portions of the plurality of leaflets; wherein the plurality of leaflets are attached to the cuff and the underwire via at least one suture that pierces the cuff and at least one of the plurality of leaflets and wraps around the underwire before piercing the cuff a second time.
 15. A prosthetic heart valve comprising: a stent having a collapsed condition and an expanded condition, the stent having a proximal end, a distal end and a plurality of cells, each cell being formed by a plurality of struts; an underwire disposed around a perimeter of the stent; and a valve assembly secured to the stent, the valve assembly including a cuff and a plurality of leaflets, each of the plurality of leaflets having a pair of attachment portions, a free edge extending between the pair of attachment portions, and a belly portion extending between the pair of attachment portions and disposed opposite the free edge, a portion of the underwire having a shape that conforms to belly portions of the plurality of leaflets, the cuff being coupled to the underwire and the plurality of leaflets, and the cuff being disposed between the underwire and portions of the plurality of leaflets; wherein each of the plurality of leaflets is folded at a proximal end to form a belly flap and an inner layer, the belly flap and the cuff being sandwiched between the underwire and the inner layer. 